Thai protesters tend a redshirt demonstrator who was shot in the head by government troops. The army has ordered women children to leave the redshirt camp before a final offensive. Photograph: Barbara Walton/EPA

Thailand's worsening political conflict faces a new deadline, with the government ordering all women and children to leave the redshirts' camp in central Bangkok by 3pm tomorrow before a final offensive to forcibly remove anybody remaining.

Bloodshed continued for a fourth day, with 31 people killed since Thursday in battles between anti-government protesters and soldiers.

As the army surrounded the redshirts' protest site, a second part of the city, Bon Kai, was declared a "live fire zone". Generals have warned that anybody walking into those areas will be shot on sight.

In flashpoints across the city, protesters clashed again with troops, hurling bricks and firing rockets at soldiers, who fired live rounds back. But the redshirts have also been seen in the streets carrying firearms, andtonight gun battles broke out near the protesters' sites, as troops closed in under cover of darkness. Some redshirt leaders indicated they would be prepared to return to negotiations immediately, but only if troops were withdrawn from the streets and the UN brought in to broker peace.

"We want the UN to moderate it because we do not trust anyone else. There is no group in Thailand that is neutral enough," the redshirt co-leader Nattawut Saikua said. "We have no other condition. We do not want any more losses."

The government appears determined to continue with its plan to forcibly remove the protesters. "If they really want to talk, they should not set conditions like asking us to withdraw troops," said Korbsak Sabhavasu, the prime minister's secretary-general. "They cannot make demands if they want to negotiate."

A temple within the redshirt protest site has been set up as a meeting place for people who wished to leave, but yesterday, save for a small group of elderly women and some children, the offer was largely ignored.

The army said it planned to allow neutral organisations such as the Red Cross into the protest area to encourage protesters to leave. "Whoever wants to leave, the government will organise transportation, [people] can go in any direction they want. Even men and tough guys and guards, the government will transport them out – the only condition is without weapons."

The British embassy, on the edge of the conflict zone, remains closed in Bangkok. The Foreign Office is warning against all but essential travel to the Thai capital and said fighting could break out in previously peaceful parts of the city.